Determinative Factors for the Thermochemical Generation of Electric Charges upon Combustion of Nitrate–Organic Precursors for Materials Based on Lanthanum Manganite and Cerium Dioxide
А. А. Остроушко, T. Yu. Maksimchuk, A. E. Permyakova, О. В. Русских
Abstract
Features of processes for the synthesis of nanosized complex perovskite-type oxides (lanthanum manganite) and doped cerium dioxide in combustion reactions of nitrate–polymer precursors under conditions of high-density electrical charges generation have been studied. Effect of external electromagnetic field on charges generation allowing change in the sign and magnitude of precursor charge has been established. It has been shown that the labile oxidation state of metals comprising resulting oxides is the requirement for charges generation. Examples of aluminum and zirconium oxides illustrate this conclusion by the absence of charges during precursors combustion. Inert (N2) or reducing atmosphere (N2 + CO) prevents the reversible oxidation of manganese ions in perovskite and cerium in dioxide, which in turn prevents charges formation. Addition of nitrogen (NО) and carbon oxides (CO) to nitrogen as combustion medium that suppresses charges formation does not result in their increase, hence, charges appear immediately when molecular species form during combustion. Metal carriers of precursors decrease accumulated charge due to higher electric capacity, while porous carriers also provide charge dissipation.